docs: def Q_weir_rectangular_full_SIA(h1, h2, b):
      r'''Calculates the flow rate across a full-channel rectangular weir from
      the height of the liquid above the crest of the weir, the liquid depth
      beneath it, and the width of the channel. Model from [1]_ as reproduced in
      [2]_.
  
      Flow rate is given by:
  
      .. math::
          Q = \frac{2}{3}\sqrt{2}\left(0.615 + \frac{0.000615}{h_1+0.0016}\right)
          b\sqrt{g} h_1 +0.5\left(\frac{h_1}{h_1+h_2}\right)^2b\sqrt{g} h_1^{1.5}
  
      Parameters
      ----------
      h1 : float
          Height of the fluid above the crest of the weir [m]
      h2 : float
          Height of the fluid below the crest of the weir [m]
      b : float
          Width of the channel section [m]
  
      Returns
      -------
      Q : float
          Volumetric flow rate across the weir [m^3/s]
  
      Notes
      -----
      The following limits apply to the use of this equation:
  
      0.025 < h < 0.8 m
      b > 0.3 m
      h2 > 0.3 m
      h1/h2 < 1
  
      Examples
      --------
      Example compares terribly with the Ackers expression - probable error
      in [2]_. DO NOT USE.
  
      >>> Q_weir_rectangular_full_SIA(h1=0.3, h2=0.4, b=2)
      1.1875825055400384
  
      References
      ----------
      .. [1] Normen für Wassermessungen: bei Durchführung von Abnahmeversuchen an
         Wasserkraftmaschinen. SIA, 1924.
      .. [2] Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.:
         Van Nostrand Reinhold Co., 1984.
      '''
      Q = 2/3.*2**0.5*(0.615 + 0.000615/(h1 + 0.0016))*b*g**0.5*h1 \
      + 0.5*(h1/(h1+h2))**2*b*g**0.5*h1**1.5
      return Q